This invention relates in general to magnetic tape cassette transport apparatus, and, more particularly, to a magnetic tape cassette transport/accessor assembly, which is lightweight and reliable, which is easy to remove and replace, and which requires little maintenance.
In applications in which a large amount of information is stored on electronic media (such as the storage of digital information on a plurality of magnetic tape cassettes), it is often desirable that each unit of storage (e.g., magnetic tape cassette), be accessed in a minimum amount of time. For example, it is desirable to minimize the time required to change over from one cassette to another cassette used in a magnetic tape record/reproduce device. Where the cassette storage system includes a large number of cassette storage compartments, it is also desirable that the cassette be transported between a storage compartment and a record/reproduce device, in a gentle manner which minimizes damage to the cassette by eliminating rough or jerky movements in the cassette transport device. It is also desirable that the cassette transport/accessor assembly be reliable, be easy to remove and replace, require little maintenance, and have a long operating life.
In storage systems which include a matrix of horizontal and vertical storage locations, apparatus for loading and unloading articles from the storage locations have been proposed which are heavy, difficult to remove and replace, and difficult to maintain. Thus, U.S. Pat. No. 3,557,977, issued Jan. 26, 1971, entitled "Load Detecting Device For Warehousing System", discloses a warehousing system including a powered load carrier for inserting and removing loads relative to storage locations of a storage system. The load carrier includes a frame which travels on upper and lower horizontal rails by means of fixedly mounted wheels. The frame carries an elevator which travels vertically. Both horizontal and vertical travel of the load carrier is effected by motors mounted on the load carrier. The disclosed apparatus is disadvantageous because of the weight of the actuating motors and motor mounts and the inconvenience of fixedly mounting wheels on the frame to facilitate horizontal travel. Thus, the load carrier is difficult to remove and replace, is difficult to maintain and is susceptible to jerky and rough movement. A similar apparatus is disclosed in U.S. Pat. No. 4,113,119, issued Sept. 12, 1978, entitled "Apparatus For Loading Articles Onto Vertically Spaced Horizontally Disposed Shelves". As disclosed, the article loading apparatus is manually driven, thus eliminating heavy motors on the apparatus. However, the apparatus is mounted for horizontal travel on fixedly mounted wheels, making it difficult to maintain and to remove and replace.
Several devices have been proposed for moving articles in which the devices are mounted on V-shaped wheels which travel on horizontal V-shaped rails. See, e.g., U.S. Pat. No. 4,363,Z57, issued Dec. 14, 1982, entitled "Strikedown Service Mechanism For A Vertical Launching System"; U.S. Pat. No. 4,099,10Z, issued July 4, 1978, entitled "Movable Feeding Apparatus For High Shelf Storage Devices"; U.S. Pat. No. 2,980,Z65, issued Apr. 18, 1961, entitled "Transfer Crane". However, the devices disclosed in each of these patents utilizes actuating motors mounted on the devices which increases the weight of the device thus making it harder to remove and replace and to maintain. Moreover, the devices are mounted on fixedly mounted wheels which makes for rougher handling of articles being carried.